Piston



March 5, 1946. c. s. ,CLARK PISTON Filed Oct. 2, 1941 f ATTORNEYPatented Mar. 5, 1946 UNITED STATES PATENT OFFICE'v rls'roN Cornelius S.Clark, Norfolk, Va. Application October 2, 1941, Serial No. 413,259

8 Claims.

This invention relates to pistons, and more particularly to such inwhich a sealing ring or diaphragm is provided for minimizing leakagebetween piston and cylinder.

The principal object of my invention, generally considered, is toconstruct a piston of improved design in which sealing means, additionalto the ordinary piston rings, is provided for minimizing leakage betweenpiston and cylinder, and where its length may be shortened by pivotingthe associated connecting rod thereto near its head end, rather thannear the skirt edge.

Another object of my invention is to provide a piston having a sealingring or diaphragm of thin metal disposed between its head end ring andthe portion thereof defining the head side of the ring groove, said ringbeing angular in section rather than nat so that an inner flange isprovided for engagement with the bottom of the groove, locking means,such as a wire, overlying said ange for holding said sealing ring inplace in its groove.

A further object of my invention is the provision of a piston with thesealing strip adjacent the outer surface of its head, said strip beingreceived in an extension of the normal vhead and piston ring groove andheld in place by a locking wire disposed therein and engaging a lateralextension on said strip.

A still further object of my invention is to provide a piston having agroove normally receiving an oil ring, with ports leading from saidgroove to the interior of the piston for feeding oil from the exteriorpiston surface past the wrist pin and back into the crank case of theengine.

Another object of my invention is the provision of a piston pivoted to aconnecting rod by a wrist pin, with special wrist pin retainers forpreventing longitudinal movement of said pin while allowing rotationthereof.

A further object of my invention is the provision of a novel form ofpiston comprising a head with a skirt depending therefrom, a, capthreaded or otherwise connected to said skirt and carrying wrist pinbosses normally near the piston head, and an outer or bottom flange onsaid cap dening a Wall of a groove for holding an oil ring.

Other `objects or advantages of the invention, relating to theparticular arrangement and construction of the various parts, willbecome apparent as the description proceeds.

Referring to the drawing:

Figure 1 is an axial sectional view of a piston, associated rings and awrist pin, embodying my invention, portions of the associated cylinderhead, cylinder, and connecting rod being also shown.

Figure 2 is a plan view of the head end of the piston.

Figure 3 is an enlarged axial sectional view co-rresponding with theupper right-hand corner of the piston shown in Figure 1.

Figure 4 is an enlarged fragmentary sectional view on the line IV-IV ofFigure l, in the direction of the arrows.

Figure 5 is a view corresponding generally with Figure 1, but omittingthe cylinder and cylinder head portion, and showing a modication.

Figure 6 is a sectional view on the line VI-VI of Figure 5, in thedirection of the arrows.

One of the problems in the construction of pistons, and especially thosefor internal combustion engines, is the loss of power due to leakagebetween the engaging walls of the cylinder and its piston. This isminimized by the employment of resilient piston rings in associatedgrooves in the outer or cylindrical surface of thel piston, which ringsbear against the engaging cylindrical surface of the cylinder and tendto prevent leakage thereby. However. it has been found that leakage alsooccurs between the rings and their grooves, so that a serious loss ofpower results, especially after said rings have Worn loose.

In my pending application, Serial No. 363,855,

led November 1, 1940, I have described and claimed a flexible sealingring or diaphragm of thin metal disposed between the surface of theconventional piston ring toward the outer surface of the piston headportion and the adjacent wall, defining the ring groove, so thatcylinder pressure causes tight engagement between said thin metal ringand the adjacent conventional piston ring, thereby opposing pressureloss therebetween. The inner edge of said ring, being tightly embeddedin a Icorresponding extension of the conventional piston ring groove,said ring is not only held in place but pressure loss therebeneathprevented. l

In accordance with my present invention, I have improved on theconstruction of the sealing or diaphragm ring and its mode of connectionto the piston, as well as provided other improve,- ments, suchas thedisposition of the wrist pin in close proximity to the piston head,thereby making it possible Ato employ either a longer connecting rod, ashorter piston, or a smaller engine, in accordance with the improvementdesired in the construction. v

Referring to the drawing in detail, and first lustrated in Figures 1 to4 inclusive, the reference character II designates a piston embodying myinvention, comprising a relatively thick head portion I2 formed, in thepresent instance, with a, pair of peripheral grooves. I3 and I4, forreceiving piston ring means which may be either double, as indicated bythe rings I5 and I8- in the groove I2 or single as indicated by the ringI1 and the groove I4. The rings I5 and I8 may be considered as pressurerings, and the ring I1 as an oil ring, although they all, of course,function to mlnimizeloss of pressure. A skirt portion, I8, extends fromthe peripheral portion of the head I0, and is desirably formedrelatively thin, as illustrated.

From that portion of the piston adjacent to the junction between thehead and skirt portions, extends an inwardly projecting annular flangeI9, rigidifying the skirt portion and providing a base from whichproject, in the direction of the free edge of said skirt, bosses 2I and22 providing bearings for a wrist pin 28 which passes therethrough andis shown hollow in the present embodiment. 'I'he skirt I8 is apertured,as indicated at 23 and 24, to a permit insertion and removal of thewrist pin 20. After placing the pin, the same is desirably held againstundesirable axial movement by means of special retainers 25 and 26,formed, as shown most clearly in Figure 4, generally like hairpins withintermediate portions bulged, as indicated at 21 and 28. These retainersare formed of a resilient material, such as spring steel wire, so thatthey may be snapped in place in wrist pin grooves 29 and 3|. Aconnecting rod 45 is pivotally united to the Wrist pin with a bushing 46disposed therebetween.

In order to minimize leakage along the surface between the piston II andthe cylinder 41, the cylinder head being indicated at 48 and both formedhollow to receive cooling water indicated at 49 and 5I, I provide asealing or diaphragm ring 52, shown most clearly in Figure 3. This ring52 is preferably formed of flexible material such as alloy steel,stainless steel, copper, brass, or the like, about .0l inch thick, withthe inner peripheral portion bent axially to form a cylindrical ange 53which will, when pushed into the groove I3, project away from the outerend surface of the piston head and in the same direction as. that isparallel to, the skirt I8 of the piston.

The sealing member 52 is of such a size that, when clamped in place inthe extension 54 of the ring groove I 3, as by means of a wire 55 whichmay be formed of copper, holding the flange 53 against the bottom of theauxiliary groove 54, its outer edge 56 is flush with theoutercylindrical surface 51 of the piston II. The ring 52 may be placed inposition generally like a piston ring, as by being out at one place toallow for entry, Spiraled into the groove, and held in place by the wire55, which may initially be slightly larger than the width of the grooveextension 54 remaining after the ring 52 is positioned, and forced tothe position shown in Figure 3 to hold the member 52 tightly in place.The ends of the ring 52 are desirably secured together by silver solderor other brazing material. However, in view of the gripping ring 55,tightly holding the flexible sealing ring 52 in place, it is notnecessary to solder the ends of said sealing ring.

A considering the embodiment of my invention il- The outer part of thehead portion I2 is desirably beveled, as indicated at 58, to allow fluidfrom the outer portion of the cylinder to press against the outersurface of the ring 52 and hold -rings I5 and I5 axially of the piston.Leakage it in tight sealingmgement with the ring I8. In this way leakagebetween piston and cylinderisminlmixed,astherings I5and I6are forcedtogether by pressure on the outer surface of said ring 52, minimizingloss of pressure between the annular outer surface of the ring I5 andthe piston head, as well as between the inner cylindrical surface ofsaid ring and the groove I 3 'Leakage betweentne rings I5 and Is and theother surfaces is minimized because of the pressure exerted by theflexible sealing ring 52 on the between the piston head and the sealingring 52 is minimized because the angular extension 53 of said sealingring is pressed in a tight engagement with the bottom of thesupplemental groove 54 by the gripping ring or retainer 55.

Thering IIflmetionsasanoil ringinone of the customary piston ringgrooves I4. This groove is here provided with passages 5I extending tothe interior of the piston for returning oil which gets by the ring I1and feeding it to the wrist pin 2l and connecting rod 45. It will,therefore, be seen that I have made a radical improvement in pistonconstruction for minimizing loss of pressure between piston andcylinder.

Referring now to the embodiment of my invention, illustrated in Figures5 and 6, there is shown a piston 52 comprising a head portion 53 and askirt portion 84. The head portion is, as in the preceding embodiment,formed with a groove receiving piston ring means 56. Although said meansis in the present embodiment formed as a single ring, it may, ifdesired, be two rings like those designated I5 and I6 of 'the precedingembodiment. The groove 55 also receives a flexible sealing or diaphragmring 51, desirably identical with the ring 52 of the precedingembodiment, and held in a supplemental groove or one extending from thehead side of the groove 65, like the auxiliary groove 54 of thepreceding embodiment, by a flexible wire E8, like that designated 55 insaid first embodiment.

The head portion 53, dening the groove 65, is desirably beveled, asindicated at 69, for a reason similar to the beveling 58 of the irstembodiment, so that the piston 62 is provided with sealing meansidentical with those of the piston I l.

In the present embodiment, however, the skirt portion 54 of the piston52 is provided with threads, indicated at 1I, and a cap 12 is providedwith cooperating threads 13, for uniting it thereto, as indicated. Anydesired means may be provided, such as a cotter pin or screw 14, forpreventing the cap 12 from unintentionally becoming loosened from theskirt 54. The cap 'I2 desirably has an outer ilange 15 which, when theparts are assembled, defines the outer or lower wall of a groove 18,formed by notching the outer edge of the skirt 54 to receive the ring orrings 11, which may function as an oil seal, like the ring I1 of theirst embodiment, or may be additional to a ring like I1 of the rstembodiment. A gasket or sealing ring 8II may be secured between the capflange I9 and the skirt 64, like the sealing ring 'II of my applicationSerial No. 363,855, previously referred to.

The inner portion of the cap 12 is provided with bosses 18 and 19,apertured as indicated at 8| and 82, to provide bearings for receivingthe hollow wrist pin 83. Said wrist pin, as in the preceding embodiment.may, after assembly with said portions and the connecting rod 84 andbushing 85, be held against axial movement by retainers 86 and 81,such"-\as Hthose' designated 25 and 26 in the first embodiment.

It will, therefore, be seen that a piston is provided in which the wristpin 83 is much closer to the head than in conventional construction. Itwill also be seen that application of the piston ring J1 is facilitatedby making the groove receiving the same in two parts, completed uponassembly of the piston head and skirt with a cap functioning as aAwristpin carrier and comprising. bearings holding the wrist pin.

From the foregoing disclosure, that Ihave provided a piston which is notonly improved from the standpoint of minimizing pressure loss but valsowith regard to the disposition of the 'wrist pin, whereby' it ispossible, if desired, to economize by decreasing the size of the enginewithout loss of power or other undesirable results.

It will also be understood that, whereas in one instance I have shown apair of lrings in a groove and in other instances only one ring in eachgroove, it iscontemplatedto use one or a plurality of rings in anygroove, as may be desired in a given case.

Although preferred embodiments of my invention have been disclosed, itwill be understood that modifications may be madeA within the spirit andscope of the inventionfas defined by the appended claims. v

Iclaim: i

1. In combination, a piston comprising` head and skirt portions, agroove in said piston, a piston ring in said groove, a flexible sealingring of thin metal disposed between the surface of said piston ringtoward the outer end surface of v said head portion and the adjacentwall defining said groove, the inner portion of said sealing ringterminating in a generally cylindrical flange.

projecting away from the'outer end surface of said head and received ina corresponding fsup-L plementary groove extending fromthe head-aside ofsaid ring groove, to close the space `between the inner cylindricalsurface of the piston ring and the bottom of said groove, and meansencircling said fiange to'hold said sealing ring in engagement with thebottom of said supplementary groove.

2. In combination, a piston comprising head and skirt portions, a groovein said piston, a pistn ring in said groove, a flexible sealing ring ofthin 'material disposed between the surface of said piston ring towardthe outer end surface of said head portion and the adjacent walldefining said groove, the inner portion of said sealing ring terminatingin a generally cylindrical flange projecting toward the piston skirt,the said adjacent wall defining said groove being beveled to admit fluidto the head surface of said sealing ring to cause it to press againstsaid piston ring and minimize pressure loss, and a wire memberencircling said flange to hold said sealing ring in engagement` with thebottom of said it will lbe seen.,

3. In combination with a piston. a groove therein, a sealing ring formedof thin material, provided with a flange or cylindrical projection, andmeans holding said ring in place in said groove, comprising a wirepressing said flange in place.

4. A piston with a groove, piston ring means therein, said groove beingformed with a supplementary portion at a side toward the head portionthereof, a sealing ring received in said supplementary portion andhaving an axial projection, and means engaging said axial projection andholding said ring in place.

5. A piston with a groove, piston ring means therein, said groove beingformed with a supplementary portion at a side toward the head Dortionthereof, a sealing ring received in said supplementary portion andhaving an axial projection, and means engaging said axial projection andholding said ring in place, said means comprising a wire ring in saidgroove engaging said axial projection and holding it in the bottom ofsaid supplementary portion.

6. In combination, a piston comprising head and skirt portions, a groovein said piston, a piston ring in said groove, a flexible sealing ringring toward the outer end surface of said head portion and the adjacentwall defining the said groove, the interior portion of said sealing ringterminating in a generally cylindrical flange, projecting away from theend surface of said head portion and received in a correspondingsupplemental groove extending from the head of said ring groove, toclose the space between the interior cylindrical surface of the pistonring and the bottom of said groove, means formed separately from andencircling said flange to hold said sealing ring in place in saidgroove, a second groove adjacent to the end of the skirt portion, a`piston ring in said groove, and a gasket cooperating with said secondpiston ring.

7. A piston with a-groove, piston ring means therein, said groove havingan inward annular extension, a sealing ring received in said groove andextension and having a cylindrical flange projecting from its inner edgeportion, and means in said extension overlying said flange for holdingsaid ring in place.

8. In combination, a piston, a groove in said piston, a piston ring insaid groove, a flexible sealing ring of thin metal disposed between theouter surface of said piston ring and the adjacent surface of saidpiston to close the space between the inner cylindrical surface of thepiston ring and the bottom of said groove, the inner portion of saidsealing ring terminating in a flange projecting away from the outer endsurfaceof the piston, and means formed separately from and encirclingsaid flange to hold said sealing ring in place in said groove.

CORNELIUS S. CLARK.

of thin metal disposed between the surface of saidv

